1. Field of the Invention
The present invention relate to a burner apparatus for use in a glass furnace, and more particularly to a burner apparatus which is used in a glass furnace incorporating a plurality of pairs of burners, each pair of burners being provided at the diametrically opposite locations of the furnace and operated alternately, and which is suitable for overheat protection of the burner which is not in operation.
2. Description of the Related Art
In a glass furnace for melting large batches of glass, a plurality of pairs of burners are provided to form a flame over the glass surface. FIG. 6 shows a conventional glass furnace 32 which incorporates a plurality of pairs of burners. Each pair of burners 10 is provided at the diametrically opposite locations of the glass furnace 32. A combustion air supply opening 33 is formed slightly above each of the burners 10, and a regenerative heat exchanger 34 is installed at the combustion air supply opening 33.
In the glass furnace 32 of the above structure, when using the burner 10 on the left side of the furnace, combustion air is supplied through the combustion air supply opening 33 and the heat exchanger 34 on the left side of the furnace, and exhaust heat is recovered by the heat exchanger 34 on the right side of the furnace. When using the burner 10 on the right side of the furnace, combustion air is supplied through the combustion air supply opening 33 and the heat exchanger 34 on the right side of the furnace, and exhaust heat is recovered by the heat exchanger 34 on the left side of the furnace. In this manner, the burner 10 and the heat exchanger 34 on either side of the furnace are used alternately during operation of the glass furnace.
As a fuel which is supplied to the burner, fuel oil is usually employed. As a medium for spraying fuel oil, pressurized air is supplied to the burner 10. As shown in FIG. 7, the burner 10 is inserted into an opening 35a of a burner tile 35 which is provided in a furnace wall 32a of the glass furnace 32. A clearance is formed between the inner circumferential surface of the opening 35a and the burner 10. When spraying fuel oil from the burner 10 by pressurized air, air outside the furnace is drawn in through the clearance around the burner 10. The forward end portion of the burner 10 is cooled by the air flowing therearound. When using a pair of burners alternately, the burner which is not in operation is subject to radiation heat from the burner in operation, thus being damaged. Therefore, in order to cool the burner which is not in operation, the burner is required to eject a small quantity of pressurized air. The burner is cooled by pressurized air, and air which is drawn in from the outside of the furnace through the clearance around the burner.
However, when the burner is in operation, a large quantity of air is drawn in from the outside of the furnace through the clearance, thus lowering temperature in the furnace and thereby lowering unit requirement for fuel oil. That is, fuel consumption increases.
Therefore, it is desirable to dispense with air for cooling the burner. As a burner which does not need a cooling air, there has heretofore been proposed a burner jacket in Japanese laid-open utility model publication No. 61-13136. According to the disclosed arrangement, a burner has a forward end portion composed of a water cooled double pipe whose tip end contacts a burner tile.
However, in the burner disclosed in the above publication, a front surface of the forward end of the burner facing the interior of the furnace is not cooled by cooling water, thus the front surface of the burner is elevated to a high temperature. As a result, carbon in fuel oil sticks to the interior of the burner and blocks up fuel oil passage, and a desired flame is not formed in the furnace. Therefore, maintenance works are frequently required to remove carbon which sticks to the interior of the burner after detaching the burner from the furnace. When detaching the burner from the furnace, maintenance workers are exposed to radiation heat from the opening of the burner tile.